<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../vue.js"></script>
</head>

<body>
    <div id="app">
        <input type="text" v-model="first">
        <select v-model="Symbol_"> 
            <option value="+">+</option>
            <option value="-">-</option>
            <option value="*">*</option>
            <option value="/">/</option>
        </select>
        <input type="text" v-model="second">
        <button @click="result">=</button>
        <input type="text" v-model="end">
    </div>
</body>
<script>
    const vm = new Vue({
        el: '#app',
        data: {
            first: "",
            second: "",
            end: "",
            Symbol_: '+'
        },
        methods: {
            result() {
                this.end = eval(`${this.first} ${this.Symbol_} ${this.second}`);
            }
        }
    })
</script>

</html>